Water Intake Calculator
Work out how much water to drink a day from your weight, your exercise and the weather where you live.
Water Intake Calculator
Water a day
3.00
- Glasses of 250 ml12
- From your weight2.15
- Extra for exercise0.35
- Extra for the weather0.50
Works out in your browser. Nothing you type is sent anywhere.
In short: Water Intake Calculator
At 65 you need about 2.15 litres a day before anything else, plus 0.35 for the exercise entered and 0.50 for the weather, which comes to 3.00 litres or 12 glasses. Food and other drinks count towards it as well.
What is Water Intake?
Daily water intake is a guideline amount of fluid for your body size, with extra added for exercise and for a hot climate.
How is Water Intake calculated?
Multiply weight in kilograms by a figure in millilitres per kilogram, then add an allowance for each half hour of exercise and a further amount for a hot or very hot climate. The total is converted to litres and to glasses.
- Lthe litres of fluid a day
- wweight in kilograms
- mthe millilitres per kilogram used as a guideline
A worked example
| Weight (kg) | 65 |
|---|---|
| Exercise a day (minutes) | 30 |
| Weather where you live | Hot or humid |
| Result | |
| Water a day | 3.00 |
| Glasses of 250 ml | 12 |
| From your weight | 2.15 |
| Extra for exercise | 0.35 |
| Extra for the weather | 0.50 |
Every figure in this table is produced by the same calculation the tool above runs.
How to use this water intake calculator
- Enter your weight in kilograms.
- Enter how many minutes of exercise you do on a typical day.
- Choose the climate where you actually live.
- Read the total in litres, and in glasses if that is easier to count.
Questions people ask
Does tea, coffee and food count?
Yes. Most fluid in a normal diet comes from drinks other than plain water, and food contributes a surprising amount, especially fruit, dal and curd. The figure here is total fluid, not plain water alone. Drinking it all as water is not necessary.
Is the eight-glasses rule right?
It is a rough average that ignores body size, activity and climate, all three of which matter a great deal in India. A large person training in summer needs far more than a small person in an air-conditioned office. That is why this tool asks for all three.
Can I drink too much water?
Yes, though it is uncommon. Drinking far beyond thirst over a short period can dilute the body's sodium, which is dangerous. Anyone with kidney or heart conditions should follow their doctor's limit rather than a general figure.
How do I tell whether I am drinking enough?
Thirst and the colour of your urine are more reliable day to day than any calculation: pale is usually fine and dark usually means more fluid. Use the figure here as a target to aim near, not a quota to hit exactly.
Accuracy and sources
For general information. Not medical advice.
Checked by the Daytoolz team on 16 October 2026. How we check our tools.
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